Field of the Invention
This invention relates generally to devices for storing thermal energy and, more particularly, to devices that convert and store solar radiation in the form of thermal energy. Even more particularly, the invention relates to portable thermal storage systems.
Description of the Background Art
Thermal energy storage systems are a fast growing and evolving technology. Some systems convert solar energy into thermal energy and store it in some type of thermal storage medium (e.g., NaNO2, NaNO3, CaCi2, LiF, KNO3, etc.). Typically, this is done in large facilities that provide energy to multiple consumers. Such facilities often employ several light focusing devices, both light permissive (e.g. Fresnel lens) and reflective (e.g. parabolic mirror), to heat some type of large thermal storage device such as, for example, a fluid reservoir, a pipe network, etc.
Although such facilities provide useful clean energy, they are stationary and, therefore, can only provide energy to consumers that are located relatively close to the facility. In an effort to provide energy to more remote locations, portable thermal energy storage systems have been developed. Such systems typically include a small light focusing device that heats a discrete thermal storage device via sunlight.
There are several challenges with current portable thermal energy storage systems. For example, thermal storage devices of portable thermal energy storage systems typically have to be small so as to facilitate their portability. Of course, small thermal storage devices have an inherently low thermal energy storage capacity. In order to increase the thermal energy storage capacity of such devices, their size must be increased. As the size of the thermal storage device is increased, however, the portability of the overall system is proportionally decreased.
What is needed, therefore, is a thermal energy storage system that has a higher thermal energy storage capacity and improved portability.